U.S. patent application number 11/176274 was filed with the patent office on 2006-06-22 for organometallic complex and organic electroluminescent devices utilizing the same.
This patent application is currently assigned to INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE. Invention is credited to Miao-Tsai Chu, Tien-Shou Shieh, Mei-Rurng Tseng, Shu-Tang Yeh.
Application Number | 20060134462 11/176274 |
Document ID | / |
Family ID | 36596253 |
Filed Date | 2006-06-22 |
United States Patent
Application |
20060134462 |
Kind Code |
A1 |
Yeh; Shu-Tang ; et
al. |
June 22, 2006 |
Organometallic complex and organic electroluminescent devices
utilizing the same
Abstract
An organometallic complex. The organometallic complex has
formula (I): ##STR1## wherein M is a transition metal comprising
Ir, Pt, Pd, or Rh, A is a C.sub.3-20 aryl, C.sub.3-20 cycloalkyl,
or C.sub.3-20 heterocyclic ring containing O, N, or S,
R.sub.1.about.R.sub.4 are the same or different and comprise H,
halogen atoms, trifluoromethyl, C.sub.1-10 alkyl, C.sub.3-10 aryl,
C.sub.3-10 cycloalkyl, or C.sub.3-10 heterocyclic ring containing
O, N, or S, C is an acetyl acetone group ##STR2## or picolinic acid
group ##STR3## wherein D, E, and F are the same or different and
comprise H, halogen atoms, trifluoromethyl, C.sub.1-20 alkyl,
C.sub.1-20 alkyl halide, C.sub.3-10 aryl, or C.sub.3-20
heterocyclic ring containing O, N, or S, and when M is Ir or Rh, m
is 1.about.3, n is 0.about.3, and m+n=3 and when M is Pt or Pd, m
is 1.about.2, n is 0.about.2, and m+n=2. The invention also
provides an organic electroluminescent device utilizing the
organometallic complex.
Inventors: |
Yeh; Shu-Tang; (Taichung
County, TW) ; Shieh; Tien-Shou; (Taipei City, TW)
; Tseng; Mei-Rurng; (Hsinchu City, TW) ; Chu;
Miao-Tsai; (Taipei County, TW) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
INDUSTRIAL TECHNOLOGY RESEARCH
INSTITUTE
|
Family ID: |
36596253 |
Appl. No.: |
11/176274 |
Filed: |
July 8, 2005 |
Current U.S.
Class: |
428/690 ;
257/102; 257/E51.044; 313/504; 313/506; 428/917; 544/225 |
Current CPC
Class: |
H01L 51/0081 20130101;
C09K 2211/1007 20130101; H01L 51/007 20130101; H05B 33/14 20130101;
C07F 15/0033 20130101; H01L 51/5016 20130101; H01L 51/0085
20130101; H01L 51/0059 20130101; C09K 2211/1044 20130101; H01L
51/0062 20130101; C09K 11/06 20130101; C09K 2211/1051 20130101;
C09K 2211/185 20130101 |
Class at
Publication: |
428/690 ;
428/917; 313/504; 313/506; 257/102; 257/E51.044; 544/225 |
International
Class: |
H01L 51/54 20060101
H01L051/54; H05B 33/14 20060101 H05B033/14 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2004 |
TW |
93140052 |
Claims
1. An organometallic complex having formula (I): ##STR40## wherein
M is a transition metal comprising Ir, Pt, Pd, or Rh, A is a
C.sub.3-20 aryl, C.sub.3-20 cycloalkyl, or C.sub.3-20 heterocyclic
ring containing O, N, or S, R.sub.1.about.R.sub.4 are the same or
different and comprise H, halogen atoms, trifluoromethyl,
C.sub.1-10 alkyl, C.sub.3-10 aryl, C.sub.3-10 cycloalkyl, or
C.sub.3-10 heterocyclic ring containing O, N, or S, C is an acetyl
acetone group ##STR41## or picolinic acid group ##STR42## wherein
D, E, and F are the same or different and comprise H, halogen
atoms, trifluoromethyl, C.sub.1-20 alkyl, C.sub.1-20 alkyl halide,
C.sub.3-10 aryl, or C.sub.3-20 heterocyclic ring containing O, N,
or S, and when M is Ir or Rh, m is 1.about.3, n is 0.about.3, and
m+n=3 and when M is Pt or Pd, m is 1.about.2, n is 0.about.2, and
m+n=2.
2. The organometallic complex as claimed in claim 1, wherein D, E,
and F comprise methyl, ethyl, isopropyl, sec-butyl, phenyl,
thiophenyl, benzothiophenyl, furanyl, napthalenyl, or
pyridinyl.
3. The organometallic complex as claimed in claim 1, wherein the
organometallic complex has formula ##STR43## (IV), wherein M is a
transition metal comprising Ir, Pt, Pd, or Rh,
R.sub.1.about.R.sub.22 are the same or different and comprise H,
halogen atoms, trifluoromethyl, C.sub.1-10 alkyl, C.sub.3-10 aryl,
C.sub.3-10 cycloalkyl, C.sub.3-10 heterocyclic ring containing O,
N, or S, alkoxy, thioalkyl, or amino, C is an acetyl acetone group
##STR44## or picolinic acid group ##STR45## wherein D, E, and F are
the same or different and comprise H, halogen atoms,
trifluoromethyl, C.sub.1-20 alkyl, C.sub.1-20 alkyl halide,
C.sub.3-10 aryl, or C.sub.3-20 heterocyclic ring containing O, N,
or S, and when M is Ir or Rh, m is 1.about.3, n is 0.about.3, and
m+n=3 and when M is Pt or Pd, m is 1.about.2, n is 0.about.2, and
m+n=2.
4. The organometallic complex as claimed in claim 3, wherein D, E,
and F comprise methyl, ethyl, isopropyl, sec-butyl, tert-butyl,
phenyl, thiophenyl, benzothiophenyl, furanyl, napthalenyl, or
pyridinyl.
5. The organometallic complex as claimed in claim 1, wherein the
organometallic complex comprises ##STR46## ##STR47## ##STR48##
wherein C is an acetyl acetone group ##STR49## or picolinic acid
group ##STR50## and D, E, and F are the same or different and
comprise H, halogen atoms, trifluoromethyl, C.sub.1-20 alkyl,
C.sub.1-20 alkyl halide, C.sub.3-10 aryl, or C.sub.3-20
heterocyclic ring containing O, N, or S, m is 1.about.3, n is
0.about.3, and m+n=3.
6. The organometallic complex as claimed in claim 5, wherein D, E,
and F comprise methyl, ethyl, isopropyl, sec-butyl, tert-butyl,
phenyl, thiophenyl, benzothiophenyl, furanyl, napthalenyl, or
pyridinyl.
7. The organometallic complex as claimed in claim 1, wherein the
organometallic complex comprises ##STR51## ##STR52## ##STR53##
wherein C is an acetyl acetone group ##STR54## or picolinic acid
group ##STR55## and D, E, and F are the same or different and
comprise H, halogen atoms, trifluoromethyl, C.sub.1-20 alkyl,
C.sub.1-20 alkyl halide, C.sub.3-10 aryl, or C.sub.3-20
heterocyclic ring containing O, N, or S, m is 1.about.3, n is
0.about.3, and m+n=3.
8. The organometallic complex as claimed in claim 7, wherein D, E,
and F comprise methyl, ethyl, isopropyl, sec-butyl, tert-butyl,
phenyl, thiophenyl, benzothiophenyl, furanyl, napthalenyl, or
pyridinyl.
9. The organometallic complex as claimed in claim 1, wherein the
organometallic complex comprises ##STR56## ##STR57## ##STR58##
wherein C is an acetyl acetone group ##STR59## or picolinic acid
group ##STR60## and D, E, and F are the same or different and
comprise H, halogen atoms, trifluoromethyl, C.sub.1-20 alkyl,
C.sub.1-20 alkyl halide, C.sub.3-10 aryl, or C.sub.3-20
heterocyclic ring containing O, N, or S, m is 1.about.3, n is
0.about.3, and m+n=3.
10. The organometallic complex as claimed in claim 9, wherein D, E,
and F comprise methyl, ethyl, isopropyl, sec-butyl, tert-butyl,
phenyl, thiophenyl, benzothiophenyl, furanyl, napthalenyl, or
pyridinyl.
11. The organometallic complex as claimed in claim 1, wherein the
organometallic complex is a luminescent material.
12. The organometallic complex as claimed in claim 1, wherein the
organometallic complex is a red phosphorescent dopant.
13. An organic electroluminescent device, comprising: a pair of
electrodes; and an organic electroluminescent layer installed
between the electrodes, comprising an organometallic complex as
claimed in claim 1.
14. The organic electroluminescent device as claimed in claim 13,
wherein the organic electroluminescent layer comprises an emitting
layer comprising the organometallic complex.
15. The organic electroluminescent device as claimed in claim 14,
wherein the organometallic complex is a red luminescent dopant.
16. The organic electroluminescent device as claimed in claim 13,
wherein the organic electroluminescent layer comprises a hole
transport layer, a hole blocking layer, an electron transport
layer, or a buffer layer.
17. The organic electroluminescent device as claimed in claim 13,
wherein the organic electroluminescent device has a luminescent
efficiency of about 1.5.about.6.51 lm/W.
18. The organic electroluminescent device as claimed in claim 13,
wherein the organic electroluminescent device has a brightness of
about 3.5.about.15.5 cd/A.
19. The organic electroluminescent device as claimed in claim 13,
wherein the organic electroluminescent device has a luminescent
wavelength of about 600.about.660 nm.
20. The organic electroluminescent device as claimed in claim 13,
wherein the organic electroluminescent device has a CIEx value of
about 0.66.about.0.70 and a CIEy value of about
0.30.about.0.33.
21. The organic electroluminescent device as claimed in claim 13,
wherein the organic electroluminescent device has an internal
quantum efficiency of about 25.about.100%.
Description
BACKGROUND
[0001] The present invention relates to an organometallic complex,
and more specifically to an organometallic complex used in an
organic electroluminescent device.
[0002] Organic electroluminescent devices are popular in flat panel
display due to their high illumination, light weight,
self-illumination, low power consumption, simple fabrication, rapid
response time, wide viewing angle, and no backlight
requirement.
[0003] When an external electric field is applied to an organic
electroluminescent device, electrons and holes are injected from
cathode and anode, respectively, and then recombined to form
excitons. Energy is further transported from excitons to
luminescent molecules with continuous application of an electric
field. Finally, luminescent molecules emit light converted from
energy. A common organic electroluminescent device structure
comprises an ITO anode, a hole transport layer, an emitting layer,
a hole blocking layer, an electron transport layer, and a cathode.
A complex organic electroluminescent device, however, may further
comprise a hole injection layer disposed between an anode and a
hole transport layer or an electron injection layer disposed
between a cathode and an electron transport layer to improve
injection efficiency of carriers, reducing driving voltage or
increasing recombination thereof.
[0004] After a luminescent molecule absorbs specific energy,
potential energy of electrons in an excited state may be released
through fluorescence and phosphorescence. Fluorescence is produced
by return of electrons from singlet excited state to ground state.
Phosphorescence, however, is produced during a return of triplet
excited state to ground state. In a fluorescent electroluminescent
device, although 75% excitons arrive at triplet excited state,
their potential energy cannot be released through emission light.
Thus, only 25% internal quantum efficiency can be acquired,
significantly reducing external quantum efficiency to lower than
5%. Nevertheless, in phosphorescent materials, potential energy of
excitons in triplet excited state can be fully released through
emission light, increasing internal quantum efficiency from 25% to
100%. Phosphorescent luminescent materials are composed of dopants
and hosts, wherein dopants containing heavy atoms are preferable.
Due to strong spin-orbital coupling from heavy atoms, singlet and
triplet orbits can be effectively hybridized, increasing transition
probability of excitons between singlet and triplet excited state
and reducing half-life of excitons in triplet state. Thus,
phosphorescent luminescent materials exhibit four times the
luminescence of fluorescents.
[0005] Currently, red fluorescent materials comprise DCJTB (Kodak)
or Pl (Idemitsu). The initial red fluorescent dopant developed from
Kodak Corporation is DCM with luminescent efficiency of 78% and
wavelength of 596nm, and its wavelength may alter with doping
concentration. The optimal doping concentration is about 0.5%, and
luminescent efficiency may achieve 2.3%. Unfortunately, DCM emits
orange light, not the red light required. Also Kodak Corporation
provides DCM-2 and DCJTB with increased steric hindrance, albeit
with emission light still orange. Kodak Corporation further
provides an electroluminescent device comprising DCJTB as well as a
yellow luminescent dopant, Rubrene, to increase energy transfer
efficiency and shift luminescent wavelength to the red light
region. Nevertheless, the fabrication thereof is complicated. The
optimal luminescent efficiency of related red fluorescent materials
is merely 31 m/W with lifetime thereof also merely 10000 hours.
Thus, development of red phosphorescent materials is desirable.
Presently, a preferable red phosphorescent material is
2,3,7,8,12,13,17,18-octaethyl-12H,23Hporphine-platinum(II) (PtOEP)
with wavelength of 650 nm, luminescent efficiency of 2.41 lm/W, a
CIEx value of 0.7, a CIEy value of 0.3, and lifetime exceeding 8000
hours. Although luminescent characteristics of PtOEP are
acceptable, applications thereof are limited due to complicated
preparation and high cost. Thompson and Forrest provide another red
phosphorescent material,
bis(2-(2'-benzo[4,5-a]thienyl)pyridinato-N,C.sup.3')iridium(acetylacetona-
te) [Btp.sub.2Ir(acac)], with luminescent efficiency of 4.71 lm/W,
wavelength of 610 nm, a CIEx value of 0.67, and a CIEy value of
0.33. This material, however, still emits red-orange light.
[0006] As well as PtOEP and Btp.sub.2Ir(acac), other phosphorescent
materials have been provided. As disclosed in E.P. Pat. No.
1434286, A Ir complex with various coordination groups is provided,
comparing effects of various coordination groups on luminescent
characteristics such as luminescent wavelength and efficiency. As
disclosed in U.S. Pre-Grant Pat. No. 2002024293, a blue
phosphorescent Ir complex with a luminescent wavelength greater
than 500 nm and external quantum efficiency exceeding 5% is
provided. As disclosed in U.S. Pre-Grant Pat. No. 2002034656 and
2003017361, Ir complexes with luminescent wavelengths 425 nm, 475
nm, 500 nm, 575 nm, and 615 nm distributing from blue to red-orange
light regions is provided.
SUMMARY
[0007] The invention provides an organometallic complex having
formula (I): ##STR4##
[0008] wherein M is a transition metal comprising Ir, Pt, Pd, or
Rh, A is a C.sub.3-20 aryl, C.sub.3-20 cycloalkyl, or C.sub.3-20
heterocyclic ring containing O, N, or S, R.sub.1.about.R.sub.4 are
the same or different and comprise H, halogen atoms,
trifluoromethyl, C.sub.1-10 alkyl, C.sub.3-10 aryl, C.sub.3-10
cycloalkyl, or C.sub.3-10 heterocyclic ring containing O, N, or S,
C is an acetyl acetone group ##STR5## or picolinic acid group
##STR6## wherein D, E, and F are the same or different and comprise
H, halogen atoms, trifluoromethyl, C.sub.1-20 alkyl, C.sub.1-20
alkyl halide, C.sub.3-10 aryl, or C.sub.3-20 heterocyclic ring
containing O, N, or S, and when M is Ir or Rh, m is 1.about.3, n is
0.about.3, and m+n=3 and when M is Pt or Pd, m is 1.about.2, n is
0.about.2, and m+n=2.
[0009] The invention also provides an organic electroluminescent
device comprising a pair of electrodes and an organic
electroluminescent layer installed therebetween, utilizing the
disclosed organometallic complex.
[0010] A detailed description is given in the following embodiments
with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The invention can be more fully understood by reading the
subsequent detailed description and examples with references made
to the accompanying drawings, wherein:
[0012] FIG. 1 is a cross section of an organic electroluminescent
device of the invention.
DETAILED DESCRIPTION
[0013] The invention provides an organometallic complex having
formula (I): ##STR7##
[0014] In formula (I), M is a transition metal with d.sup.6
electron orbits such as Ir, Pt, Pd, or Rh, preferably Ir. A is a
C.sub.3-20 aryl, C.sub.3-20 cycloalkyl, or C.sub.3-20 heterocyclic
ring containing O, N, or S, preferably phenyl or heterocyclic ring
containing S. R.sub.1.about.R.sub.4 are the same or different and
comprise H, halogen atoms, trifluoromethyl, C.sub.1-10 alkyl,
C.sub.3-10 aryl, C.sub.3-10 cycloalkyl, or C.sub.3-10 heterocyclic
ring containing O, N, or S, preferably F atom or trifluoromethyl. C
is an acetyl acetone group ##STR8## or picolinic acid group
##STR9## wherein D, E, and F are the same or different and comprise
H, halogen atoms, trifluoromethyl, C.sub.1-20 alkyl, C.sub.1-20
alkyl halide, C.sub.3-10 aryl, or C.sub.3-20 heterocyclic ring
containing O, N, or S, such as methyl, ethyl, isopropyl, sec-butyl,
tert-butyl, phenyl, thiophenyl, benzothiophenyl, furanyl,
napthalenyl, or pyridinyl. When M is Ir or Rh, m is 1.about.3, n is
0.about.3, and m+n=3. When M is Pt or Pd, m is 1.about.2, n is
0.about.2, and m+n=2.
[0015] The specific organometallic complexes provided by the
invention are divided into three groups (1).about.(3) with
different coordination groups:
[0016] (1) 4-phenyl quinazoline coordination group: ##STR10##
##STR11## ##STR12##
[0017] (2) 4-phenyl thieno[2,3-d]pyrimidine coordination group:
##STR13## ##STR14## ##STR15##
[0018] (3) 4-phenyl thieno[3,2-d]pyrimidine coordination group:
##STR16## ##STR17## ##STR18##
[0019] In the forgoing complexes, C is an acetyl acetone group
##STR19## or picolinic acid group ##STR20## and D, E, and F are the
same or different and comprise H, halogen atoms, trifluoromethyl,
C.sub.1-20 alkyl, C.sub.1-20 alkyl halide, C.sub.3-10 aryl, or
C.sub.3-20 heterocyclic ring containing O, N, or S, such as methyl,
ethyl, isopropyl, sec-butyl, tert-butyl, phenyl, thiophenyl,
benzothiophenyl, furanyl, napthalenyl, or pyridinyl. Additionally,
m is 1.about.3, n is 0.about.3, and m+n=3.
[0020] The compound of formula (I) is prepared as follows. First, a
coordination compound such as phenyl quinazoline or phenyl
thienopyrimidine is prepared by general synthesis. Next, the
coordination compound, a metal halide, solvent, and deionized water
are added to a flask with thermal reflux for about 16.about.20
hours. The metal halide may be IrCl.sub.3*H.sub.2O, and the solvent
may be ethylene glycol ethyl ether. After cooling to room
temperature and filtration, collected solids are washed with a
small quantity of solvent such as methanol. An organometallic dimer
is prepared after drying. Next, the organometallic dimmer, a salt
such as Na.sub.2CO.sub.3, a bidentate compound, and solvent such as
ethylene glycol ethyl ether, are added to a flask with thermal
reflux for about 16.about.20 hours. The bidentate compound
comprises acetyl acetone or picolinic acid. After cooling to room
temperature and filtration, collected solids are washed with a
small quantity of solvent such as methanol. An organometallic
complex (formula (I)) containing two coordination groups and a
bidentate group (n=1) is prepared after drying. Another
organometallic complex without bidentate groups (n=0) is prepared
as follows. First, the foregoing organometallic complex containing
two coordination groups and a bidentate group (n=1), a coordination
compound, and solvent such as glycerol, are added to a flask with
thermal reflux at 150.about.200.degree. C. for about 6.about.10
hours. After cooling to room temperature and filtration, collected
solids are washed with a small quantity of solvent such as
methanol. An organometallic complex containing three coordination
groups (n=0) is prepared after drying.
[0021] Original hydrogen atoms in a benzene ring are replaced by
fluorine atoms. The modified complex structure provides several
advantages, for example, high luminescent efficiency due to
low-frequency vibrations of C--F bonds, effectively avoiding
excited radiationless decay, low evaporation temperature, less
self-quenching by alteration of stack structures of molecules, high
electron mobility, and altered light color of red phosphorescent
organic electroluminescent material by modification of HOMO-LUMO
energy levels with fluoridized molecules.
[0022] Due to strong spin-orbital coupling, electrons in a singlet
excited state of a d.sup.6 Ir complex may easily migrate to a
triplet excited state by Metal to Ligand Charge Transfer (MLCT) and
hybrid .pi.-.pi.* coordination orbits, resulting in increased
phosphorescent luminescent efficiency. Emission wavelength of the
phosphorescent complex appears in a red light region of about
600.about.660 nm. Additionally, the invention provides a more
simple synthesis of the novel red luminescent material.
[0023] The invention also provides an organic electroluminescent
device comprising a pair of electrodes and an organic
electroluminescent layer installed therebetween, utilizing the
disclosed organometallic complex as formula (I).
[0024] The organic electroluminescent layer comprises an emitting
layer comprising the disclosed organometallic complex used as a red
luminescent dopant. Hosts of the emitting layer comprise CBP, TCTA,
CzTT, TPBI, TAZ, BAlq, MCP, UGHI, UGH2, or UGH3. The organic
electroluminescent layer further comprises a hole transport layer,
a hole blocking layer, an electron transport layer, or a buffer
layer. The hole transport layer comprises HTM2, TPD, NPB, PPD,
TBPB, spiro-TAD, spiro-NPB, TPTE2, TPTE1, NTPA, or DNPD. The hole
blocking layer comprises BPhen BCP, BAlq, CF--X, TAZ, or CF--Y. The
electron transport layer comprises t-Bu-PBD, Alq.sub.3, BeBq, TAZ,
Almq3, BAlq, or TPBI. The buffer layer may comprise LiF or
Li.sub.2O. The foregoing abbreviations represent the following
structures. ##STR21## ##STR22## ##STR23## ##STR24## ##STR25##
##STR26## ##STR27##
[0025] A method of fabricating an organic electroluminescent device
is further provided. An anode is provided on a substrate and a hole
transport layer is evaporated on the anode to a thickness of about
400.about.600 .ANG.. A Ir complex (dopant) and host are then
co-evaporated on the hole transport layer to form an emitting layer
at a thickness of about 150.about.250 .ANG., with dopant/host
volume ratio about 4.about.8%. Next, a hole blocking layer is
evaporated on the emitting layer to a thickness of about
100.about.200 .ANG.. An electron transport layer is evaporated on
the hole blocking layer to a thickness of about 150.about.250
.ANG.. A buffer layer is evaporated on the electron transport layer
to a thickness of about 5.about.10 .ANG.. Finally, a cathode is
evaporated on the buffer layer to a thickness of about
1000.about.1400 .ANG..
[0026] The organic electroluminescent device has luminescent
efficiency of about 1.5.about.6.51 lm/W, brightness of about
3.5.about.15.5 cd/A, a luminescent wavelength of about
600.about.660 nm, a CIEx value of about 0.66.about.0.70, and a CIEy
value of about 0.30.about.0.33.
EXAMPLES
Example 1
Preparation of Compound 1
[0027] ##STR28##
[0028] (1) 8 g 2-aminobenzophenone, 91 g formamide, and 25 g formic
acid were added to a 250 ml flask and stirred at 150.degree. C. for
2 hours. After returning to room temperature, 200 ml deionized
water was added and filtered. Collected solids were then washed
with a small quantity of deionized water and dried. 6.3 g yellow
compound 1a was finally prepared with yield of 74% after
re-crystallization with ethanol. The melting point thereof was
100.about.101.degree. C. and its .sup.1H-NMR (CDCl.sub.3) data were
9.42 (1H, s, 2-H) and 8.28-7.15 (9H, m, ArH). The reaction
according to step (1) was ##STR29##
[0029] (2) 4 g compound 1a, 2 g IrCl.sub.3*H.sub.2O, 60 ml ethylene
glycol ethyl ether, and 20 ml deionized water were added to a 150
ml flask under nitrogen gas with thermal reflux for 18 hours. After
returning to room temperature and filtration, collected solids were
then washed with a small quantity of methanol. After drying, 3.2 g
yellow compound 1b was finally prepared with yield of 76%. The
reaction according to step (2) was ##STR30##
[0030] (3) 3.2 g compound 1b, 2.7 g Na.sub.2CO.sub.3, 5 ml acetyl
acetone, and 120 ml ethylene glycol ethyl ether were added to a 250
ml flask under nitrogen gas with thermal reflux for 18 hours. After
returning to room temperature and filtration, collected solids were
then washed with a small quantity of methanol. After drying, 2.8 g
yellow compound 1 was finally prepared with yield of 89%. The
reaction according to step (3) was ##STR31##
Example 2
Preparation of Compound 2
[0031] ##STR32##
[0032] (1) 8 g 2-amino-thiophen-3-yl-phenyl-methanone, 91 g
formamide, and 25 g formic acid were added to a 250 ml flask and
stirred at 150.degree. C. for 2 hours. After returning to room
temperature, 200 ml deionized water was added and filtered.
Collected solids were then washed with a small quantity of
deionized water and dried. 5.3 g yellow compound 2a was finally
prepared with yield of 62% after re-crystallization with ethanol.
The reaction according to step (1) was ##STR33##
[0033] (2) 5.3 g compound 2a, 2.5 g IrCl.sub.3*H.sub.2O, 90 ml
ethylene glycol ethyl ether, and 30 ml deionized water were added
to a 250 ml flask under nitrogen gas with thermal reflux for 18
hours. After returning to room temperature and filtration,
collected solids were then washed with a small quantity of
methanol. After drying, 4.2 g yellow compound 2b was finally
prepared with yield of 78%. The reaction according to step (2) was
##STR34##
[0034] (3) 4.2 g compound 2b, 3.5 g Na.sub.2CO.sub.3, 6.5 ml acetyl
acetone, and 160 ml ethylene glycol ethyl ether were added to a 250
ml flask under nitrogen gas with thermal reflux for 18 hours. After
returning to room temperature and filtration, collected solids were
then washed with a small quantity of methanol. After drying, 2.5 g
yellow compound 2 was finally prepared with yield of 65%. The
reaction according to step (3) was ##STR35##
Example 3
Preparation of Compound 3
[0035] ##STR36##
[0036] (1) 7 g 4-chlorothieno[3,2-d]pyrimidine, 5.6 g phenyl boric
acid, and 0.14 g PPh.sub.3 were added to a 250 ml flask under
nitrogen gas. 120 ml K.sub.2CO.sub.3 (2M) and 80 ml 1,2-dimethoxy
ethane (DME) were then added and heated to 60.degree. C. Next, 0.3
g Pd(OAc).sub.2 was added with thermal reflux for 8 hours. After
returning to room temperature, organo-layer was extracted by ethyl
acetate. Remaining water in the organo-layer was then removed by
adding MgSO.sub.4. Finally, collected solids were purified by a
silica gel chromatographic column (ethyl acetate:n-butane=1:4) to
form 7.2 g white compound 3a with yield of 76%. The reaction
according to step (1) was ##STR37##
[0037] (2) 5 g compound 3a, 2.4 g IrCl.sub.3*H.sub.2O, 90 ml
ethylene glycol ethyl ether, and 30 ml deionized water were added
to a 250 ml flask under nitrogen gas with thermal reflux for 18
hours. After returning to room temperature and filtration,
collected solids were then washed with a small quantity of
methanol. After drying, 3.8 g yellow compound 3b was finally
prepared with yield of 61%. The reaction according to step (2) was
##STR38##
[0038] (3) 3.8 g compound 3b, 3.2 g Na.sub.2CO.sub.3, 6 ml acetyl
acetone, and 150 ml ethylene glycol ethyl ether were added to a 250
ml flask under nitrogen gas with thermal reflux for 18 hours. After
returning to room temperature and filtration, collected solids were
then washed with a small quantity of methanol. After drying, 2 g
yellow compound 3 was finally prepared with yield of 51%. The
reaction according to step (3) was ##STR39##
Example 4
Fabrication of Organic Electroluminescent Device
[0039] Referring to FIG. 1, a method of fabricating an organic
electroluminescent device is disclosed according to the following
example, in which an ITO anode 100 was provided on a substrate and
washed with cleaning agent and deionized water. After drying, NPB
was evaporated on the ITO anode 100 to form a hole transport layer
110 at a thickness of 500 .ANG.. Ir complex (compound 1, dopant)
and CBP (host) were then co-evaporated on the hole transport layer
110 to form an emitting layer 120 at a thickness of 200 .ANG.. The
dopant/host volume ratio thereof was 6%. Next, BCP was evaporated
on the emitting layer 120 to form a hole blocking layer 130 at a
thickness of 150 .ANG.. Next, Alq.sub.3 was evaporated on the hole
blocking layer 130 to form an electron transport layer 140 at a
thickness of 200 .ANG.. Next, LiF was evaporated on the electron
transport layer 140 to form a buffer layer 150 at a thickness of 5
.ANG.. Finally, Al was evaporated on the buffer layer 150 to form a
cathode 160 at a thickness of 1200 .ANG..
[0040] Various brightness, luminescent efficiency, wavelengths, and
CIE values between the devices utilizing compound 1, 2, and 3,
respectively, provided by the invention and the devices utilizing
related luminescent materials, such as PtOEP, Btp2Ir(acac), and
Piq2Ir(acac) were compared as shown in Table 1. TABLE-US-00001
TABLE 1 Luminescent Brightness efficiency Wavelength CIE (x, y)
materials (cd/A) (lm/W) (nm) values Compound 1 3.75 1.82 648 (0.70,
0.30) Compound 2 15.02 6.10 600 (0.57, 0.42) Compound 3 14.01 5.31
605 (0.59, 0.40) PtOEP 2.22 1.08 650 (0.69, 0.30) Btp2Ir (acac)
3.40 1.65 620 (0.62, 0.35) Piq2Ir (acac) 4.33 2.10 624 (0.67,
0.32)
[0041] The results indicate that the red organic electroluminescent
material of the invention provides better brightness, luminescent
efficiency, and CIE values. Additionally, synthesis thereof is also
simple, meeting economic benefits.
[0042] While the invention has been described by way of example and
in terms of preferred embodiment, it is to be understood that the
invention is not limited thereto. To the contrary, it is intended
to cover various modifications and similar arrangements (as would
be apparent to those skilled in the art). Therefore, the scope of
the appended claims should be accorded the broadest interpretation
so as to encompass all such modifications and similar
arrangements.
* * * * *